Engine-performance monitor and control system

Abstract

An engine-performance monitor for determining the relative combustion efficiencies of the cylinders of a multiple cylinder internal combustion engine permits monitoring of engine performance to test engine fuel distribution system and ignition system control strategies. The system can also be incorporated into a feedback system for controlling the performances of the various individual cylinders of a multiple cylinder internal combustion engine.

What is claimed is: 
     
       1. A system for controlling the performances of the individual cylinders of a multiple cylinder internal combustion engine comprising an engine ignition generator and spark distribution system, means for coupling the ignition generator and spark distribution system to the various cylinders, means for sensing engine crankshaft position, a clock for generating a time base, means for sensing the top dead center point of the power stroke in each cylinder, means for calculating crankshaft speed, means for coupling the clock and the crankshaft position sensor to the crankshaft speed calculator, means for calculating combustion efficiencies of the various cylinders, means for coupling the combustion efficiency calculating means to the clock, to the crankshaft position sensor, and to the means for sensing the top dead center point, the combustion efficiency calculating means calculating the combustion efficiency of each cylinder by determining a measure of the speed of the crankshaft during a portion of each cylinder's stroke in response to signals from the clock and the crankshaft position sensor and comparing the measures of crankshaft speed determined during the strokes of cylinders, means for calculating ignition timing for the various cylinders to control the performances of the various cylinders, means for coupling the combustion efficiency calculator to the ignition timing calculator and means for coupling the ignition timing calculator to the ignition generator and spark distribution system. 
     
     
       2. The system of claim 1 wherein the combustion efficiency calculator comprises a data processor for utilizing the signals from the time base generator, the crankshaft position sensor and the means for sensing the top dead center point to provide a set of data points about the top dead center point. 
     
     
       3. A system for controlling the performances of the individual cylinders of a multiple cylinder internal combustion engine comprising an engine fuel distribution system, means for coupling the fuel distribution system to the various cylinders, means for sensing engine crankshaft position, a clock for generating a time base, means for sensing the top dead center point of the power stroke in each cylinder, means for calculating crankshaft speed, means for coupling the clock and the crankshaft position sensor to the crankshaft speed calculator, means for calculating combustion efficiencies of the various cylinders, means for coupling the combustion efficiency calculating means to the means for sensing the top dead center point, to the means for sensing the crankshaft position and to the clock, means for calculating a fuel distribution parameter for the various cylinders to control the performance of the various cylinders, means for coupling the combustion efficiency calculator means to the means for calculating the fuel distribution parameter and means for coupling the fuel distribution parameter calculation means to the engine fuel distribution system. 
     
     
       4. The system of claim 3 wherein the combustion efficiency calculator comprises a data processor for utilizing the signals from the time base generator, the crankshaft position sensor and the means for sensing the top dead center point to provide a set of data points about the top dead center point. 
     
     
       5. The system of claim 3 wherein the fuel distribution parameter is the amount of fuel which is to be metered into each respective cylinder. 
     
     
       6. The system of claim 3 wherein the fuel distribution parameter is the time in the respective cylinder's operating cycle at which the fuel is metered into the cylinder. 
     
     
       7. An adaptive idle speed control system for an internal combustion engine, comprising an engine fuel distribution system, means for coupling the engine fuel distribution system to the engine's cylinders including a throttle for controlling the flow of fuel through the fuel distribution system for controlling the speed of the engine, means for sensing engine crankshaft position, a clock for generating a time base, means for calculating crankshaft speed, means for coupling the clock and the crankshaft position sensor to the crankshaft speed calculator, means for calculating an index of performance for each of the various cylinders, means for coupling the performance index calculating means to the clock and to the crankshaft position sensor, the performance index calculating means calculating the index of performance of each cylinder by determining crankshaft speed during a portion of each cylinder's stroke in response to signals from the clock and the crankshaft position sensor and comparing the crankshaft speeds determined during the strokes of cylinders, means for calculating engine roughness based upon the indices of performance, means for coupling the roughness calculating means to the performance index calculating means, means for comparing the roughness to a roughness set point and adjusting the throttle in response to the comparison to control the idle speed of the engine, means for coupling the comparing and adjusting means to the throttle, means for determining the roughness set point in response to the indices of performance, and means for coupling the roughness set point determining means to the performance index calculating means. 
     
     
       8. The system of claim 7 wherein the roughness set point determining means changes the roughness set point in response to a predetermined number of indices of performance for successive cylinders exceeding a predetermined limit. 
     
     
       9. The system of claim 8 wherein the limit comprises an indication of excessive degradation of the index of performance from one cylinder to the next. 
     
     
       10. The system of claim 8 wherein changing the roughness set point causes the comparing and adjusting means to increase the engine idle speed.